This invention relates to a fluid valve for use in highly corrosive environments and, more particularly, to a fluid valve having a valve disc with a zirconium oxide coated surface for closing on a valve seat.
Steel and cast iron are employed as structural materials for piping, valves and pumps throughout industrial plants because of their cost effectiveness and general suitability for many services. However, the service lives of many of these components may be drastically shortened by only trace amounts of corrosive species contaminating otherwise noncorrosive fluids. Thus, for example, check valves used in hydraulic lines of vacuum pumps employed in a chlorine gas service were found to last for only a few days because the highly corrosive nature of trace amounts of chlorine in the hydraulic fluid literally dissolved the movable valve discs which shut against the valve seat. Thus, a valve having a substantially longer service life is needed for this service.
U.S. Pat. No. 4,808,092 to Funke discloses a precision metering pump which employs cubic zirconium oxide pump and valve parts. This material is employed primarily because of its transparency, but also because of its chemical inertness. Funke discloses that the zirconium oxide parts are made by grinding a shape to final size and then polishing, which is a costly process.